Internal combustion engine comprising at least one camshaft

ABSTRACT

An internal combustion engine, having at least one camshaft, which is mounted in the radial direction via at least one bearing block supplied with bearing fluid, wherein in the region of the bearing block, two sealing rings are provided, which are axially spaced apart from each other and which seal an annular chamber supplied with bearing fluid and located between the camshaft and the associated bearing block at least partially in the axial direction.

The present invention relates to an internal combustion engine comprising at least one camshaft which is mounted in the radial direction in at least one bearing block supplied with a bearing fluid.

Camshafts are usually mounted in internal combustion engines, i.e., in particular in a cylinder crankcase (for overhead camshafts, the mounting takes place in the cylinder head) of the same, by means of bearing blocks supplied with bearing fluid. For this, the bearing blocks comprise a bearing fluid feed channel which transports bearing fluid, in particular bearing oil, and which supplies an annular chamber located between the camshaft and the associated bearing block with bearing fluid, i.e., for example with oil, thereby mounting the camshaft in the radial direction. By the rotational movement of the camshaft and by the pressure difference within the annular chamber, the bearing fluid is transported in the axial direction and discharges at an axial end of the annular chamber into the cylinder crankcase/oil chamber of the cylinder head. After discharging, it usually accumulates in a bearing fluid pump and from there it is fed again by means of a bearing fluid pump to the bearing block or annular chamber. However, such a configuration has principally the disadvantage that during the operation of the camshaft, a relatively large amount of bearing fluid has to be pumped through the annular chamber, whereby a significant capacity of the bearing fluid pump is required. At the same time, a relatively high volume of bearing fluid has to be provided. Due to the regulations which become increasingly stricter, the automotive industry is more and more required to reduce the energy consumption of internal combustion engines, thereby reducing the emission.

The invention is concerned with the problem to offer an improved embodiment of an internal combustion engine by means of which in particular the energy consumption can be reduced.

This problem is solved according to the invention by the subject matter of the independent claim 1. Advantageous embodiments are subject matter of the dependent claims.

The invention is based on the general idea to at least partially seal an annular chamber previously open in the axial direction between a camshaft and a bearing block within an internal combustion engine, thereby reducing a flow of bearing fluid through the bearing. By reducing the bearing fluid flow, on the one hand, a bearing fluid pump with a considerably reduced delivery rate can be used and, on the other, the required amount of bearing fluid can be reduced. Thus, due to the lower overall bearing fluid flow flowing through the at least one bearing, the energy consumption of the bearing fluid pump and thus the energy consumption of the whole internal combustion engine can be reduced, whereby the same consumes less fuel and thereby produces less emissions. For at least partially sealing the annular chamber between the camshaft and the associated bearing block, according to the invention, two sealing rings are provided which are axially spaced apart from one another.

In an advantageous development of the solution according to the invention, at least one of the sealing rings is configured as a sealing ring which is closed in circumferential direction or as an open sealing ring. A closed sealing ring can be made, for example, of plastic or metal and can be assembled during the fabrication of the internal combustion engine by means of a particularly thermal joining method or, in case of an embodiment made of plastic, by means of an elastic elongation/compression. In contrast, rings which are open in the circumferential direction, for example of the kind of a VESPEL® ring, can advantageously be used during repair and maintenance work. Such VESPEL® rings comprise teeth in the circumferential direction, which teeth engage with one another and which allows such a sealing ring to act in the axial direction in a sealing manner, despite its embodiment which is open in the circumferential direction. By configuring such sealing rings as plastic parts, the same can be produced, for example, with a cost-effective plastic injection molding method so that the additional costs for implementing the invention are comparatively small.

Suitably, at least one of the sealing rings comprises a friction- and/or wear-reducing coating. Since sealing rings are primarily intended to fulfill a sealing function, but, at the same time, should not negatively influence the operation of the internal combustion engine, such a friction-reducing coating is of particular advantage because the same does not generate an unfavorable influence on friction losses of the internal combustion machine. In contrast, a wear-reducing coating increases the service life of such sealing rings, whereby the quality of the internal combustion engine and the reliability of the same can be increased.

In a further advantageous embodiment of the solution according to the invention, a groove is provided on the camshaft and/or the bearing block with which groove an associated sealing ring engages. Such a groove forms a guide for the associated sealing ring so that the same can be fixed in place in particular with respect to its axial direction. If an opposing groove is provided on the bearing block as well as on the camshaft, a sealing ring engaging therewith can absorb at the same time at least small axial forces and serves in this case at least as support for an axial bearing which is usually provided anyway.

Further important features and advantages arise from the sub-claims, from the drawings, and from the associated description of the figures based on the drawings.

It is to be understood that the above mentioned features and the features yet to be explained hereinafter can be used not only in the respectively mentioned combination but also in other combinations or alone without departing from the scope of the present invention.

Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in the following description in more detail, wherein identical reference numbers refer to identical, or similar, or functionally identical components.

In the figures, schematically,

FIG. 1 shows a sectional view through a camshaft in the region of a bearing block comprising a bearing sealed according to the invention,

FIG. 2 shows an illustration as in FIG. 1, but in a different embodiment,

FIG. 3 shows an illustration as in FIG. 1, but in a further embodiment,

FIGS. 4 a,b each show sealing rings open in the circumferential direction in the region of a joint.

According to the FIGS. 1 to 3, an internal combustion engine 1 according to the invention comprises a camshaft 2 which is mounted in the radial direction via at least one bearing block 4 which is supplied with bearing fluid 3.

According to FIG. 1, the bearing block 4 is only partially drawn. An annular chamber 5 supplied with bearing fluid 3, in particular oil, extends between the camshaft 2 and the bearing block 4, wherein the supply of this annular chamber 5 with bearing fluid 3 is usually carried out via a bearing fluid feed channel 6 which runs in the bearing block 4 and opens out in the annular chamber 5 (cf. FIGS. 2 and 3). Once the bearing fluid 3 is flowed into the annular chamber 5 it is transported, due to a pressure gradient and due to a rotational movement of the camshaft 2, in the axial direction and discharges at an axial end of the bearing block 4 into an interior of the crankcase. In order to reduce a comparatively high bearing fluid flow in connection with a high delivery rate of a non-shown bearing fluid pump, the invention proposes to provide in the region of the bearing block 4, two sealing rings 7 and 7′ which are axially spaced apart from one another and which seal the annular chamber 5 supplied with bearing fluid and located between the camshaft 2 and the associated bearing block 4 at least partially in the axial direction. By the sealing rings 7, 7′, the bearing fluid or the oil, respectively, is thus retained longer in the annular chamber 5, whereby, on the one hand, the bearing fluid pump supplying the annular chamber 5 with bearing fluid can be dimensioned smaller and in a more energy-saving manner and, on the other, a total volume of a required amount of bearing fluid can be reduced. Through the axial sealing of the annular chamber 5, thus, a positive influence on the energy consumption of the internal combustion engine and thus on the emission behavior of the same can be achieved.

The sealing rings 7, 7′ can be made, for example, of plastic, in particular polytetrafluoroethylene, or metal, in particular of a casting material. They can be configured, at the same time, as sealing ring which is closed in the circumferential direction or, as shown in the FIGS. 4 a and 4 b, as sealing rings 7, 7′ which are open in the circumferential direction.

A joint 8 in the circumferential direction in the seals 7 shown according to the FIGS. 4 a and 4 b is formed like a labyrinth which also helps to limit the bearing fluid flow in the axial direction 9. Sealing rings 7, 7′ made of plastic as well as of metal can be produced in a cost-effective manner and, in addition, can have, for example, a friction- and/or wear-reducing coating, whereby friction losses within the internal combustion engine can be reduced and thereby, also energy can be saved.

Generally, the term “sealing rings” is to be understood here such that the same do not completely seal the annular chamber 5, but allow an at least small leakage flow of bearing fluid 3 which is exactly predefined with respect to its amount so that a continuous flow of bearing fluid 3 through the annular chamber 5 and thus a cooling of said bearing is ensured.

Moreover, it can be provided that a groove 10 is provided on the camshaft 2 and/or on the bearing block 4, with which groove the associated sealing ring 7 engages. According to FIG. 1, only the bearing block 4 is provided here with a recess-like groove 10, wherein according to FIG. 2, on the camshaft 2 as well as on the bearing block 4, adequate grooves 10 are provided. According to FIG. 3, the grooves provided on the bearing block 4 are not arranged opposite to each other, but interact with grooveless opposite faces of the bearing block 4 or the camshaft 2, respectively.

Closed sealing rings 7 can be inserted, for example, by an elastic elongation or by a particularly thermal joining method into the associated grooves 10 on the bearing block 4 or the camshaft 2, and thereby can be reliably fixed therein. In particular in an embodiment of opposing grooves 10 on the bearing block 4 as well as on the camshaft 2, said grooves having a small axial extension can guide the sealing ring 7 engaged therewith so that the same can serve in this case at the same time as axial bearing for the camshaft 2.

In general, with the sealing rings 7, 7′ according to the invention, a required capacity and thus a required energy consumption of a bearing fluid pump can be considerably reduced, whereby the energy consumption of the associated internal combustion engine and its emission behavior can be positively influenced. Grooves 10 which are to be provided, if necessary, as well as the sealing rings 7, 7′ themselves can be produced in a cost-effective manner and, due to the significantly reduced energy consumption, can be expected to be amortized quickly. Of course, the sealing ring 7, 7′ can also be provided between a bearing block 4 and an axially adjacent cam 11 as it is shown, for example, according to FIG. 1. 

1. An internal combustion engine, comprising; at least one camshaft, which is mounted in the radial direction via at least one bearing block supplied with bearing fluid, wherein in the region of the bearing, two sealing rings are provided, which are axially spaced apart from each other and which seal an annular chamber supplied with bearing fluid and located between the camshaft and the associated bearing block at least partially in the axial direction.
 2. The internal combustion engine according to claim 1, wherein at least one bearing fluid feed channel extending in the bearing block opens out in the annular chamber.
 3. The internal combustion engine according to claim 1, wherein at least one sealing ring is formed as the sealing ring, which is at least one of closed and open in the circumferential direction.
 4. The internal combustion engine according to claim 1, wherein at least one sealing ring is formed from at least one of a plastic and a metal.
 5. The internal combustion engine according to claim 1, wherein at least one sealing ring has at least one of a friction reducing coating and a wear reducing coating.
 6. The internal combustion engine according to claim 1, wherein at least one sealing ring is formed in such a manner that a defined leakage flow is possible.
 7. The internal combustion engine according to claim 1, wherein a groove is provided on at least one of the camshaft and the bearing block, with which the associated sealing ring engages.
 8. The internal combustion engine according to claim 1, wherein at least one sealing ring is joined to at least one of the camshaft and the bearing block.
 9. The internal combustion engine according to claim 1, wherein at least one sealing ring is formed at the same time as the axial bearing.
 10. The internal combustion engine according to claim 2, wherein at least one sealing ring is formed as the sealing ring, which is at least one of closed and open in the circumferential direction.
 11. The internal combustion engine according to claim 4, wherein at least one sealing ring is formed from at least one of a polytetrafluoroethylene (PTFE) plastic and a cast metal material.
 12. The internal combustion engine according to claim 2, wherein at least one sealing ring has at least one of a friction reducing coating and a wear reducing coating.
 13. The internal combustion engine according to claim 2, wherein at least one sealing ring is formed in such a manner that a defined leakage flow is possible.
 14. The internal combustion engine according to claim 2, wherein a groove is provided on at least one of the camshaft and the bearing block, with which the associated sealing ring engages.
 15. The internal combustion engine according to claim 2, wherein at least one sealing ring is thermally joined on at least one of the camshaft and the bearing block.
 16. The internal combustion engine according to claim 2, wherein at least one sealing ring is formed at the same time as the axial bearing. 